Method for producing a sugar stream

ABSTRACT

An improved dry grind system and method for producing a sugar stream from grains or similar carbohydrate sources and/or residues, such as for biochemical production. In particular, after saccharification and prior to a sugar conversion process, a sugar/carbohydrate stream is removed from a saccharified stream. The sugar/carbohydrate stream includes a desired Dextrose Equivalent (DE) where DE describes the degree of conversion of starch to dextrose can be produced, with the such sugar stream being available for biochemical production, e.g., alcohol production, or other processes. In addition, the systems and methods also can involve the removal of certain grain components, e.g., corn kernel components, including protein and/or fiber. Sugar stream production occurs on the front end of the system and method.

TECHNICAL FIELD

The present invention relates generally to systems and methods for usein the biochemical (e.g., biofuel), food, feed, nutrition, enzymes,amino acids, proteins, and/or pharmacy industries and, morespecifically, to improved dry grind systems and methods for producing asugar stream, such as for biochemical production.

BACKGROUND

The conventional processes for producing various types of biochemicals,such as biofuels (e.g., alcohol) and other chemicals (e.g., enzymesand/or amino acids), from grains generally follow similar procedures.Wet mill processing plants convert, for example, corn grain, intoseveral different co-products, such as germ (for oil extraction), glutenfeed (high fiber animal feed), gluten meal (high protein animal feed)and starch-based products such as alcohol (e.g., ethanol or butanol),high fructose corn syrup, or food and industrial starch. Dry grindplants generally convert grains, such as corn, into two products, namelyalcohol (e.g., ethanol or butanol) and distiller's grains with solubles.If sold as wet animal feed, distiller's wet grains with solubles arereferred to as DWGS. If dried for animal feed, distiller's dried grainswith solubles are referred to as DDGS. This co-product provides asecondary revenue stream that offsets a portion of the overall alcoholproduction cost.

With respect to the wet mill process, FIG. 1 is a flow diagram of atypical wet mill alcohol (e.g., ethanol) production process 10. Theprocess 10 begins with a steeping step 12 in which grain (e.g., corn) issoaked for 24 to 48 hours in a solution of water and sulfur dioxide inorder to soften the kernels for grinding, leach soluble components intothe steep water, and loosen the protein matrix with the endosperm. Cornkernels contain mainly starch, fiber, protein, and oil. The mixture ofsteeped corn and water is then fed to a degermination mill step (firstgrinding) 14 in which the corn is ground in a manner that tears open thekernels and releases the germ so as to make a heavy density (8.5 to 9.5Be) slurry of the ground components, primarily a starch slurry. This isfollowed by a germ separation step 16 that occurs by flotation and useof a hydrocyclone(s) to separate the germ from the rest of the slurry.The germ is the part of the kernel that contains the oil found in corn.The separated germ stream, which contains some portion of the starch,protein, and fiber, goes to germ washing to remove starch and protein,and then to a dryer to produce about 2.7 pounds to 3.2 pounds (drybasis) of germ per bushel of corn (lb/bu). The dry germ has about 50%oil content on a dry basis.

The remaining slurry, which is now devoid of germ but contains fiber,gluten (i.e., protein), and starch, is then subjected to a fine grindingstep (second grinding) 20 in which there is total disruption ofendosperm and release of endosperm components, namely gluten and starch,from the fiber. This is followed by a fiber separation step 22 in whichthe slurry is passed through a series of screens in order to separatethe fiber from starch and gluten and to wash the fiber clean of glutenand starch. The fiber separation stage 22 typically employs staticpressure screens or rotating paddles mounted in a cylindrical screen(i.e., paddle screens). Even after washing, the fiber from a typical wetgrind mill contains 15 to 20% starch. This starch is sold with the fiberas animal feed. The remaining slurry, which is now generally devoid offiber, is subjected to a gluten separation step 24 in whichcentrifugation or hydrocyclones separate starch from the gluten. Thegluten stream goes to a vacuum filter and dryer to produce gluten(protein) meal.

The resulting purified starch co-product then can undergo a jet cookingstep 26 to start the process of converting the starch to sugar. Jetcooking refers to a cooking process performed at elevated temperaturesand pressures, although the specific temperatures and pressures can varywidely. Typically, jet cooking occurs at a temperature of about 93° C.to about 110° C. (about 200° F. to about 230° F.) and a pressure ofabout 30 psi to about 50 psi. This is followed by liquefaction 28,saccharification 30, fermentation 32, yeast recycling 34, anddistillation/dehydration 36 for a typical wet mill biochemical system.Liquefaction occurs as the mixture or “mash” is held at 90 to 95° C. inorder for alpha-amylase to hydrolyze the gelatinized starch intomaltodextrins and oligosaccharides (chains of glucose sugar molecules)to produce a liquefied mash or slurry. In the saccharification step 30,the liquefied mash is cooled to about 50° C. and a commercial enzymeknown as gluco-amylase is added. The gluco-amylase hydrolyzes themaltodextrins and short-chained oligosaccharides into single glucosesugar molecules to produce a liquefied mash. In the fermentation step32, a common strain of yeast (Saccharomyces cerevisae) is added tometabolize the glucose sugars into ethanol and CO₂.

Upon completion, the fermentation mash (“beer”) will contain about 15%to about 18% ethanol (volume/volume basis), plus soluble and insolublesolids from all the remaining grain components. The solids and someliquid remaining after fermentation go to an evaporation stage whereyeast can be recovered as a byproduct. Yeast can optionally be recycledin a yeast recycling step 34. In some instances, the CO₂ is recoveredand sold as a commodity product. Subsequent to the fermentation step 32is the distillation and dehydration step 36 in which the beer is pumpedinto distillation columns where it is boiled to vaporize the ethanol.The ethanol vapor is separated from the water/slurry solution in thedistillation columns and alcohol vapor (in this instance, ethanol) exitsthe top of the distillation columns at about 95% purity (190 proof). The190 proof ethanol then goes through a molecular sieve dehydrationcolumn, which removes the remaining residual water from the ethanol, toyield a final product of essentially 100% ethanol (199.5 proof). Thisanhydrous ethanol is now ready to be used for motor fuel purposes.Further processing within the distillation system can yield food gradeor industrial grade alcohol.

No centrifugation step is necessary at the end of the wet mill ethanolproduction process 10 as the germ, fiber, and gluten have already beenremoved in the previous separation steps 16, 22, 24. The “stillage”produced after distillation and dehydration 36 in the wet mill process10 is often referred to as “whole stillage” although it also istechnically not the same type of whole stillage produced with atraditional dry grind process described in FIG. 2 below, since noinsoluble solids are present. Other wet mill producers may refer to thistype of stillage as “thin” stillage.

The wet grind process 10 can produce a high quality starch product forconversion to alcohol, as well as separate streams of germ, fiber, andprotein, which can be sold as co-products to generate additional revenuestreams. However, the overall yields for various co-products can be lessthan desirable and the wet grind process is complicated and costly,requiring high capital investment as well as high-energy costs foroperation.

Because the capital cost of wet grind mills can be so prohibitive, somealcohol plants prefer to use a simpler dry grind process. FIG. 2 is aflow diagram of a typical dry grind alcohol (e.g., ethanol) productionprocess 100. As a general reference point, the dry grind method 100 canbe divided into a front end and a back end. The part of the method 100that occurs prior to distillation 110 is considered the “front end,” andthe part of the method 100 that occurs after distillation 110 isconsidered the “back end.” To that end, the front end of the dry grindprocess 100 begins with a grinding step 102 in which dried whole cornkernels can be passed through hammer mills for grinding into meal or afine powder. The screen openings in the hammer mills or similar devicestypically are of a size 6/64 to 9/64 inch, or about 2.38 mm to about3.57 mm, but some plants can operate at less than or greater than thesescreen sizes. The resulting particle distribution yields a very widespread, bell type curve, which includes particle sizes as small as 45microns and as large as 2 mm to 3 mm. The majority of the particles arein the range of 500 to 1200 microns, which is the “peak” of the bellcurve.

After the grinding step 102, the ground meal is mixed with cook water tocreate a slurry at slurry step 103 and a commercial enzyme calledalpha-amylase is typically added (not shown). The slurry step 103 isfollowed by a liquefaction step 104 whereat the pH is adjusted to about5.2 to about 5.8 and the temperature maintained between about 50° C. toabout 105° C. so as to convert the insoluble starch in the slurry tosoluble starch. Various typical liquefaction processes, which occur atthis liquefaction step 104, are discussed in more detail further below.The stream after the liquefaction step 104 has about 30% dry solids (DS)content, but can range from about 29% to about 36%, with all thecomponents contained in the corn kernels, including starch/sugars,protein, fiber, starch, germ, grit, oil, and salts, for example. Highersolids are achievable, but this requires extensive alpha amylase enzymeto rapidly breakdown the viscosity in the initial liquefaction step.There generally are several types of solids in the liquefaction stream:fiber, germ, and grit.

Liquefaction may be followed by separate saccharification andfermentation steps, 106 and 108, respectively, although in mostcommercial dry grind ethanol processes, saccharification andfermentation can occur simultaneously. This single step is referred toin the industry as “Simultaneous Saccharification and Fermentation”(SSF). Both saccharification and SSF can take as long as about 50 hoursto about 60 hours. Fermentation converts the sugar to alcohol. Yeast canoptionally be recycled in a yeast recycling step (not shown) eitherduring the fermentation process or at the very end of the fermentationprocess. Subsequent to the fermentation step 108 is the distillation(and dehydration) step 110, which utilizes a still to recover thealcohol.

Finally, a centrifugation step 112 involves centrifuging the residualsproduced with the distillation and dehydration step 110, i.e., “wholestillage”, in order to separate the insoluble solids (“wet cake”) fromthe liquid (“thin stillage”). The liquid from the centrifuge containsabout 5% to about 12% DS. The “wet cake” includes fiber, of which theregenerally are three types: (1) pericarp, with average particle sizestypically about 1 mm to about 3 mm; (2) tricap, with average particlesizes about 500 microns; (3) and fine fiber, with average particle sizesof about 250 microns. There may also be proteins with a particle size ofabout 45 microns to about 300 microns.

The thin stillage typically enters evaporators in an evaporation step114 in order to boil or flash away moisture, leaving a thick syrup whichcontains the soluble (dissolved) solids (mainly protein andstarches/sugars) from the fermentation (25 to 40% dry solids) along withresidual oil and fine fiber. The concentrated slurry can be sent to acentrifuge to separate the oil from the syrup in an oil recovery step116. The oil can be sold as a separate high value product. The oil yieldis normally about 0.6 lb/bu of corn with high free fatty acids content.This oil yield recovers only about ⅓ of the oil in the corn, with partof the oil passing with the syrup stream and the remainder being lostwith the fiber/wet cake stream. About one-half of the oil inside thecorn kernel remains inside the germ after the distillation step 110,which cannot be separated in the typical dry grind process usingcentrifuges. The free fatty acids content, which is created when the oilis heated and exposed to oxygen throughout the front and back-endprocess, reduces the value of the oil. The (de-oil) centrifuge onlyremoves less than 50% because the protein and oil make an emulsion,which cannot be satisfactorily separated.

The syrup, which has more than 10% oil, can be mixed with thecentrifuged wet cake, and the mixture may be sold to beef and dairyfeedlots as Distillers Wet Grain with Solubles (DWGS). Alternatively,the wet cake and concentrated syrup mixture may be dried in a dryingstep 118 and sold as Distillers Dried Grain with Solubles (DDGS) todairy and beef feedlots. This DDGS has all the corn and yeast proteinand about 67% of the oil in the starting corn material. But the value ofDDGS is low due to the high percentage of fiber, and in some cases theoil is a hindrance to animal digestion and lactating cow milk quality.

Further, with respect to the liquefaction step 104, FIG. 3 is a flowdiagram of various typical liquefaction processes that define theliquefaction step 104 in the dry grind process 100. Again, the dry grindprocess 100 begins with a grinding step 102 in which dried whole cornkernels are passed through hammer mills or similar milling systems suchas roller mills, flaking mills, impacted mill, or pin mills for grindinginto meal or a fine powder. The grinding step 102 is followed by theliquefaction step 104, which itself includes multiple steps as isdiscussed next.

Each of the various liquefaction processes generally begins with theground grain or similar material being mixed with cook and/or backsetwater, which can be sent from evaporation step 114 (FIG. 2), to create aslurry at slurry tank 130 whereat a commercial enzyme calledalpha-amylase is typically added (not shown). The pH is adjusted here,as is known in the art, to about 5.2 to about 5.8 and the temperaturemaintained between about 50° C. to about 105° C. so as to allow for theenzyme activity to begin converting the insoluble starch in the slurryto soluble liquid starch. Other pH ranges, such as from pH 3.5-7.0, maybe utilized, and an acid treatment system using sulfuric acid, forexample, can be used as well for pH control and conversion of thestarches to sugars.

After the slurry tank 130, there are normally three optional pre-holdingtank steps, identified in FIG. 3 as systems A, B, and C, which may beselected depending generally upon the desired temperature and holdingtime of the slurry. With system A, the slurry from the slurry tank 130is subjected to a jet cooking step 132 whereat the slurry is fed to ajet cooker, heated to about 120° C., held in a U-tube or similar holdingvessel for about 2 min to about 30 min, then forwarded to a flash tank.In the flash tank, the injected steam flashes out of the liquid stream,creating another particle size reduction and providing a means forrecovering the injected stream. The jet cooker creates a sheering forcethat ruptures the starch granules to aid the enzyme in reacting with thestarch inside the granule and allows for rapid hydration of the starchgranules. It is noted here that system A may be replaced with a wetgrind system. With system B, the slurry is subjected to a secondaryslurry tank step 134 whereat the slurry is maintained at a temperaturefrom about 90° C. to about 100° C. for about 10 min to about 1 hour.With system C, the slurry from the slurry tank 130 is subjected to asecondary slurry tank—no steam step 136, whereat the slurry from theslurry tank 130 is sent to a secondary slurry tank, without any steaminjection, and maintained at a temperature of about 80° C. to about 90°C. for about 1 hours to about 2 hours. Thereafter, the slurry from eachof systems A, B, and C is forwarded, in series, to first and secondholding tanks 140 and 142 for a total holding time of about 60 minutesto about 4 hours at temperatures of about 80° C. to about 90° C. tocomplete the liquefaction step 104, which then is followed by thesaccharification and fermentation steps 106 and 108, along with theremainder of the process 100 of FIG. 2. While two holding tanks areshown here, it should be understood that one holding tank, more than twoholding tanks, or no holding tanks may be utilized.

In today's typical grain to biochemical plants (e.g., corn to alcoholplants), many systems, particularly dry grind systems, process theentire corn kernel through fermentation and distillation. Such designsrequire about 30% more front-end system capacity because there is onlyabout 70% starch in corn, with less for other grains and/or biomassmaterials. Additionally, extensive capital and operational costs arenecessary to process the remaining non-fermentable components within theprocess. By removing undesirable, unfermentable components prior tofermentation (or other reaction process), more biochemical, biofuel, andother processes become economically desirable.

It thus would be beneficial to provide an improved dry milling systemand method that produces a sugar stream, such as for biochemicalproduction, that may be similar to the sugar stream produced byconventional wet corn milling systems, but at a fraction of the cost andgenerate additional revenue from high value by-products, such as oil,protein, and/or fiber, for example, with desirable yield.

SUMMARY OF THE INVENTION

The present invention provides for a dry milling system and method thatproduces a sugar stream, such as for biochemical production, that may besimilar to the sugar stream produced by conventional wet corn millingsystems, but at a fraction of the cost, and generate additional revenuefrom high value by-products, such as oil, protein, and/or fiber, forexample, with desirable yield.

In one embodiment, a method for producing a sugar stream is provided andincludes mixing ground grain particles with a liquid to produce a slurryincluding starch, then subjecting the slurry to liquefaction to providea liquefied starch solution. Thereafter, at least a portion of theliquefied starch solution is subjected to saccharification to convertthe starch to simple sugars and produce a saccharified stream includingthe simple sugars. After saccharification but prior to furtherprocessing of the simple sugars, the saccharified stream is separatedinto a first solids portion and a first liquid portion including thesimple sugars, wherein the first liquid portion defines a sugar streamhaving a dextrose equivalent of at least 20 DE and a total unfermentablesolids fraction that is less than or equal to 30% of a total solidscontent.

In another embodiment, a system for producing a sugar stream is providedthat includes a slurry tank in which ground grain particles mix with aliquid to produce a slurry including starch and a liquefaction systemthat receives the slurry and provides a liquefied starch solution, andwhereat the starch begins to convert to oligosaccharides. Asaccharification system is situated after the liquefaction system andreceives at least a portion of the liquefied starch solution. Thesaccharification system converts the oligosaccharides to simple sugarsthereby producing a saccharified stream including the simple sugars. Afirst separation device receives and separates the saccharified streaminto a first solids portion and a first liquid portion including thesimple sugars, wherein the first liquid portion defines a sugar streamhaving a dextrose equivalent of at least 20 DE and a total unfermentablesolids fraction that is less than or equal to 30% of the total solidscontent. The first separation device is situated prior to any sugarconversion device that receives and processes the simple sugars toproduce a biochemical.

The features and objectives of the present invention will become morereadily apparent from the following Detailed Description taken inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate embodiments of the invention and,with a detailed description of the embodiments given below, serve toexplain the principles of the invention.

FIG. 1 is a flow diagram of a typical wet mill alcohol productionprocess;

FIG. 2 is a flow diagram of a typical dry grind alcohol productionprocess;

FIG. 3 is a flow diagram of various typical liquefaction processes in atypical dry grind alcohol production process;

FIG. 4 is a flow diagram showing a dry grind system and method forproducing a sugar stream in accordance with an embodiment of theinvention;

FIG. 5 is a flow diagram showing a dry grind system and method forproducing a sugar stream in accordance with another embodiment of theinvention;

FIG. 6 is a flow diagram showing a dry grind system and method forproducing a sugar stream in accordance with another embodiment of theinvention;

FIG. 7 is a flow diagram showing a dry grind system and method forproducing a sugar stream in accordance with another embodiment of theinvention; and

FIG. 8 is a flow diagram showing a dry grind system and method forproducing a sugar stream in accordance with another embodiment of theinvention.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

FIGS. 1 and 2 have been discussed above and represent flow diagrams of atypical wet mill and dry grind alcohol production process, respectively.FIG. 3, likewise, has been discussed above and represents varioustypical liquefaction processes in a typical dry grind alcohol productionprocess.

FIGS. 4-8 illustrate embodiments of dry grind systems and methods 200,200 a, 200 b, 300, and 300 a for producing a sugar stream from grains orsimilar carbohydrate sources and/or residues, such as for biochemicalproduction, in accordance with the present invention. As furtherdiscussed in detail below, a sugar/carbohydrate stream, which includes adesired Dextrose Equivalent (DE) where DE describes the degree ofconversion of starch to dextrose (a.k.a. glucose) and/or has had removedtherefrom an undesirable amount of unfermentable components can beproduced after saccharification and prior to fermentation (or othersugar utilization/conversion process), with such sugar stream beingavailable for biochemical production, e.g., alcohol production, or otherprocesses. In other words, sugar stream production occurs on the frontend of the systems and methods 200, 200 a, 200 b, 300, 300 a. Theremoval of certain grain components prior to saccharification can occuras well, as discussed below.

For purposes herein, in one example, the resulting sugar stream, whichmay be desirable after saccharification, but before fermentation, suchas for use in biochemical production, can be a stream where thestarch/sugars in that stream define at least a 90 DE and/or where thetotal insoluble (unfermentable) solids fraction of the stream is lessthan or equal to 7% of the total solids content in the stream. In otherwords, at least 90% of the total starch/sugar in that stream is dextroseand/or no greater than 7% of the total solids in that stream includesnon-fermentable components. In another example, the sugar stream maydefine at least 95 DE. In another example, the resulting sugar streammay define at least 98 DE. In yet another example, the starch/sugars inthe stream can define at least a 20, 30, 40, 50, 60, 70, or 80 DE. Inanother example, the total insoluble (unfermentable) solids fraction ofthe stream is less than or equal to 5% of the total solids content inthe stream. In another example, the total insoluble (unfermentable)solids fraction of the stream is less than or equal to 3% of the totalsolids content in the stream. In another example, the total insoluble(unfermentable) solids fraction of the stream is less than or equal to1%. In still another example, the total insoluble (unfermentable) solidsfraction of the stream is less than or equal to 10%, 15%, 20%, 25%, or30%. In other words, the total fermentable content (fermentable solidsfraction) of the stream may be no more than 30%, 40%, 50%, 60%, 70%,75%, 80%, 85%, 90%, 95%, 97%, or 99% of the total solids content in thestream. In another example, on a dry mass basis, the weight %fermentable material in the sugar stream that may be desired is greaterthan or equal to 80%. In another example, on a dry mass basis, theweight % fermentable material in a sugar stream is greater than or equalto 85%, 90%, 95%, 98%, or 99%.

In addition, although the systems and methods 200, 200 a, 200 b, 300,300 a described herein will generally focus on corn or kernelcomponents, virtually any type of grain, whether whole and fractionatedor any carbohydrate source, including, but not limited to, wheat,barley, sorghum, rye, rice, oats, sugar cane, tapioca, cassava, pea, orthe like, as well as other biomass products, can be used. And broadlyspeaking, it should be understood that the entire grain or biomass orless than the entire grain, e.g., corn and/or grit and/or endosperm orbiomass, may be ground and/or used in the systems and methods 200, 200a, 200 b, 300, 300 a.

With further reference now to FIG. 4, in this dry grind system andmethod 200, grains such as corn and/or corn particles, for example, canbe subjected to an optional first grinding step 202, which involves useof a disc mill, hammer mill, roller mill, pin mill, impact mill, flakingmill, grind mill, or the like, either in series or parallel, to grindthe corn and/or corn particles to particle sizes less than about 5/64inch or, in another example, less than about 10/64 inch and allow forthe release of oil therefrom to define free oil. In one example, thecorn can be ground. In one example, the screen size for separating theparticles can range from about 24/64 inch to about 2/64 inch. In anotherexample, the resulting particle sizes are from about 50 microns to about3 mm. The grinding also helps break up the bonds between the fiber,protein, starch, and germ. In one example, screen size or resultingparticle size may have little to no impact on the ability to separatethe sugar from the remaining kernel or similar raw materialcomponent(s). If the carbohydrate source is pre-ground or initially inparticulate form, the optional grind step 202 may be excluded from thesystem and method 200.

Next, the ground corn flour can be mixed with backset liquid at slurrytank 204 to create a slurry. Optionally, fresh water may be added so asto limit the amount of backset needed here. An enzyme(s), such as alphaamylase, optionally can be added to the slurry tank 204 or in a slurryblender (not shown) between the first grinding step 202 and the slurrytank 204. The slurry may be heated at the slurry tank 204 from about 66°C. (150° F.) to about 93° C. (200° F.) for about 10 min to about 120min. The stream from the slurry tank 204 contains about 0.5 lb/bu freeoil, about 1.5 lb/bu germ (particle size ranges from about 50 microns toabout 3 mm), about 1.8 lb/bu grit (particle size ranges from about 50microns to about 3 mm), which can include starch, and about 4.25 lb/bufiber (particle size ranges from about 50 microns to about 3 mm).

The stream from the slurry tank 204 next may be subjected to an optionalsecond grinding/particle size reduction step 205, which may involve useof a disc mill, hammer mill, pin mill, impact mill, roller mill, flakingmill, grind mill, or the like, to further grind the corn particles toparticle sizes less than about 850 microns and allow for additionalrelease of oil and protein/starch complexes therefrom. In anotherexample, the particle sizes are from about 300 microns to about 650 mm.The grinding further helps continue to break up the bonds between thefiber, protein, and starch and facilitates the release of free oil fromgerm particles. The stream from the second grinding/particle sizereduction step 205 contains about 0.1 lb/bu to about 1.0 lb/bu free oil.

Prior to subjecting the stream from the slurry tank 204 to the optionalsecond grinding/particle size reduction step 205, the slurry may besubjected to an optional liquid/solid separation step 206 to remove adesired amount of liquids therefrom. The liquid/solid separation step206 separates a generally liquefied solution (about 60% to about 80% byvolume), which includes free oil, protein, and fine solids (which do notneed grinding), from heavy solids cake (about 20% to about 40% byvolume), which includes the heavier fiber, grit, and germ, which caninclude bound oil, protein, and/or starch. The liquid/solid separationstep 308 uses dewatering equipment, e.g., a paddle screen, a vibrationscreen, screen decanter centrifuge or conic screen centrifuge, apressure screen, a preconcentrator, a filter press, or the like, toaccomplish separation of the solids from the liquid portion. The finesolids can be no greater than 200 microns. In another example, the finesolids are no greater than 500 microns, which is generally dependentupon the screen size openings used in the liquid/solid separationdevice(s).

In one example, the dewatering equipment is a paddle screen, whichincludes a stationary cylinder screen with a high speed paddle withrake. The number of paddles on the paddle screen can be in the range of1 paddle per 4 to 8 inches of screen diameter. In another example, thedewatering equipment is a preconcentrator, which includes a stationarycylinder screen with a low speed screw conveyor. The conveyor pitch onthe preconcentrator can be about ⅙ to about ½ of the screen diameter.The number of paddles on the paddle screen and the conveyor pitch on thepreconcentrator can be modified depending on the amount of solids in thefeed. The gap between the paddle screen and paddle can range from about0.04 to about 0.2 inch. A smaller gap gives a drier cake with highercapacity and purer fiber but loses more fiber to filtrate. A larger gapgives a wetter cake with lower capacity and purer liquid (less insolublesolid). The paddle speed can range from 400 to 1200 RPM. In anotherexample, the paddle speed can range from 800 to 900 RPM. A higher speedprovides higher capacity but consumes more power. One suitable type ofpaddle screen is the FQ-PS32 paddle screen, which is available fromFluid-Quip, Inc. of Springfield, Ohio.

The screen for the dewatering equipment can include a wedge wire typewith slot opening, or a round hole, thin plate screen. The round holescreen can help prevent long fine fiber from going through the screenbetter than the wedge wire slot opening, but the round hole capacity islower, so more equipment may be required if using round hole screens.The size of the screen openings can range from about 45 microns to about500 microns. In another example, the screen openings can range from 100to 300 microns. In yet another example, the screen openings can rangefrom 200 to 250 microns. Smaller screen openings tend to increase theprotein/oil/alcohol yield with higher equipment and operation cost,whereas larger screen openings tend to lower protein/oil/alcohol yieldwith less equipment and operation cost.

The wet cake or dewatered solids portion of the stream at theliquid/solid separation step 206 (about 60% to about 65% water) next maybe subjected to the optional second grinding/particle size reductionstep 205, as described above. After milling, the solids can be mixedwith the liquefied starch solution from the liquid/solid separation step206, as shown, to form a heavy slurry and subjected to liquefaction step207.

In particular, the liquefaction step 207 can include multiple steps asdiscussed above and shown in FIG. 3. In one embodiment, the pH can beadjusted here to about 5.2 to about 5.8 and the temperature maintainedbetween about 50° C. to about 105° C. so as to convert the insolublestarch in the slurry to soluble or liquid starch. Other pH ranges, suchas from pH 3.5 to 7.0, may be utilized and an acid treatment systemusing sulfuric acid, for example, may be used as well for pH control andfor conversion of the starches to sugars. The slurry may be furthersubjected to jet cooking whereat the slurry is fed to a jet cooker,heated to about 120° C., held for about 2 min to about 30 min, thenforwarded to a flash tank. The jet cooker creates a sheering force thatruptures the starch granules to aid the enzyme in reacting with thestarch inside the granule and for hydrating the starch molecules. Inanother embodiment, the slurry can be subjected to a secondary slurrytank whereat steam is injected directly to the secondary slurry tank andthe slurry is maintained at a temperature from about 80° C. to about100° C. for about 30 min to about one hour. In yet another embodiment,the slurry can be subjected to a secondary slurry tank with no steam. Inparticular, the slurry is sent to a secondary slurry tank without anysteam injection and maintained at a temperature of about 80° C. to about90° C. for 1 to 2 hours. Thereafter, the liquefied slurry may beforwarded to a holding tank for a total holding time of about 1 hour toabout 4 hours at temperatures of about 80° C. to about 90° C. tocomplete the liquefaction step 207. With respect to the liquefactionstep 207, pH, temperature, and/or holding time may be adjusted asdesired.

The slurry stream after the liquefaction step 207 has about 28% to about40% dry solids (DS) content with all the components contained in thecorn kernels, including starches/sugars, protein, fiber, germ, grit,oil, and salts, for example. Higher slurry streams with dry solids ofgreater than 50% may be incorporated with this system and method 200.There generally are three types of solids in the liquefaction stream:fiber, germ, and grit, which can include starch and protein, with allthree solids having about the same particle size distribution. Thestream from the liquefaction step 207 contains about 1.0 lb/bu free oil,about 1.5 lb/bu germ particle (size ranges from less about 50 microns toabout 1 mm), about 4.5 lb/bu protein (size ranges from about 50 micronsto about 1 mm), and about 4.25 lb/bu fiber (particle size ranges fromabout 50 microns to about 3 mm). A portion of the liquefied sugar streamcan be sent directly to the fermentation step 214, as discussed furtherbelow.

After the liquefaction step 207 (but before any potentialsaccharification, fermentation, or other processing of the sugarstream), so as to provide a more desirable sugar stream, at least aportion of the liquefied sugar stream can be subjected to a solid/liquidseparation step 208. In particular, the solid/liquid separation step208, which may be optional, uses any suitable filtration device, e.g., apre-concentrator, paddle screen, pressure screen, fiber centrifuge,decanter, and the like, to separate the liquid from the solid material.The screen openings can range from about 50 microns to about 500 micronsand will be selected to desirably separate the fiber, grit, and germparticles from the liquid, which primarily includes the liquefied starchsolution with small amounts of oil, free protein (mainly gluten), andstarch. In one example, the screen openings are about 50 microns.

The solids portion from the solid/liquid separation step 208 can besent, along with the optional portion of the liquefied starch solutionfrom the liquefaction step 207, to the fermentation step 214. Theliquefied starch solution from the solid/liquid separation step 208 canbe sent to the saccharification step 210 whereat complex carbohydrateand oligosaccharides are further broken down into simple sugars,particularly single glucose sugar molecules (i.e., dextrose) to producea liquefied mash.

In particular, at the saccharification step 210, the slurry stream maybe subjected to a two-step conversion process. The first part of thecook process, in one example, includes adjusting the pH to about 3.5 toabout 7.0, with the temperature being maintained between about 30° C. toabout 100° C. for 1 to 6 hours to further convert the insoluble starchin the slurry to soluble starch, particularly dextrose. In anotherexample, the pH can be 5.2 to 5.8 or 5.5, for example. In anotherexample, the temperature can be maintained at 80° C. for about 5 hours.Also, an enzyme, such as alpha-amylase may be added here. In oneexample, the amount of alpha-amylase may be from about 0.0035 wt % toabout 0.004 wt % of the slurry stream. In another example, the amount ofalpha-amylase may be from about 0.02 wt % to about 0.1 wt % of the totalstream.

The second part of the cook process, in one example, may includeadjusting the pH to about 3.5 to about 5.0, with the temperature beingmaintained between about 30° C. to about 100° C. for about 10 minutes toabout 5 hours so as to further convert the insoluble starch in theslurry to soluble starch, particularly dextrose. In another example, thepH can be 4.5. In another example, the temperature can be maintainedfrom about 54° C. (130° F.) to about 74° C. (165° F.) for about 4 hoursor up to about 60 hours. An enzyme, such as glucoamylase, also may beadded here. In one example, the amount of glucoamylase may be from about0.01 wt % to about 0.2 wt % of the slurry stream. In another example,the amount of glucoamylase may be from about 0.08 wt % to about 0.14 wt% of the slurry stream. Other enzymes (e.g., cellulase, protease,phytase, etc.) or similar catalytic conversion agents may be added atthis step or previous steps that can enhance starch conversion to sugaror yield other benefits, such as fiber or cellulosic sugar release,conversion of proteins to soluble proteins, or the release of oil fromthe germ.

A saccharified sugar stream having a density of about 1.05 grams/cc toabout 1.15 grams/cc can result here. At this point, the saccharifiedsugar stream may be no less than about 90 DE. In another example, thesaccharified sugar stream may be no less than 20, 30, 40, 50, 60, 70, or80 DE. In this example, the saccharified sugar stream may not beconsidered desirable or “clean” enough, such as for use in biochemical(e.g., biofuel) production, because the total fermentable content of thestream may be no more than 75% of the total solids content in thestream. In this example, the saccharified sugar stream can have a totalsolids fraction of about 25% to about 40%, such solids including sugar,starch, fiber, protein, germ, oil, and ash, for example. In yet anotherexample, the total fermentable content of the stream is no more than 30,40, 50, 60, or 70% of the total solids content in the stream. Theremaining solids are fiber, protein, oil, and ash, for example.

After the saccharification step 210 (but before any potentialfermentation or processing of the sugar stream), so as to provide a moredesirable sugar stream, the saccharified sugar stream can be subjectedto an optional sugar separation step 212. The sugar separation step 212filters a generally liquefied solution (about 60% to about 80% byvolume), which includes sugar, free oil, protein, fine solids, fiber,grit, and germ, and which has a total solids fraction of about 30%, witha range of about 20% to about 40%, but higher or low solids fractionscan be produced, but may not be economical here. In particular, thesugar separation step 212 can include a rotary vacuum filter,micro-filter, membrane filtration, precoat/diatomaceous earth filter,decanter, centrifuge, disc centrifuge, cyclone, dorclone, or the like,to accomplish substantial separation of the solids portion, primarilyfiber, germ, and grit, which can include protein, from the liquid sugarportion, which primarily includes sugar (e.g., dextrose), residual oil,and fine solids. The solids portion (retentate), which has a totalsolids fraction of about 39%, may be sent on to the fermentation step214, as discussed further below. In one example, the filter screen sizehere may be from about 0.1 microns to about 100 microns. In anotherexample, the filter screen size may be from about 5 microns to about 50microns. Due to the input of water, the sugar stream can have a totalsolids fraction of 20-30%. In this example, the sugar stream here may beconsidered purified or refined enough because the total insoluble(unfermentable) solids fraction of the stream is less than 7%. Inanother example, the total insoluble (unfermentable) solids fraction ofthe stream is less than or equal to 5%. In another example, the totalinsoluble (unfermentable) solids fraction of the stream is less than orequal to 3%. In another example, the total insoluble (unfermentable)solids fraction of the stream is less than or equal to 1%. In stillanother example, the total insoluble (unfermentable) solids fraction ofthe stream is less than or equal to 10%, 15%, 20%, 25%, or 30%.

The sugar separation step 212 may be replaced by, or additionallyinclude, microfiltration, ultrafiltration, carbon column filtration,filter press, flotation and/or demineralization technologies (e.g., ionexchange). Resin refining, which includes a combination of carbonfiltration and demineralization in one step, can also be utilized forrefining the sugars. Additionally, due to a low solids content of thesugar stream here, an optional evaporation step (not shown) may be addedhereafter to further concentrate the total solids fraction.

At this point, the separated sugar stream may be no less than about 90DE. In another example, the saccharified sugar stream may be no lessthan 20, 30, 40, 50, 60, 70, or 80 DE. In this example, the sugar streamhere may be considered desirable or “clean” enough, such as for use inbiochemical production, because the total insoluble (unfermentable)solids fraction of the stream is less than or equal to 7% of the totalsolids of the stream. In another example, the total insoluble(unfermentable) solids fraction of the stream is less than or equal to5%. In another example, the total insoluble (unfermentable) solidsfraction of the stream is less than or equal to 3%. In another example,the total insoluble (unfermentable) solids fraction of the stream isless than or equal to 1%. In still another example, the total insoluble(unfermentable) solids fraction of the stream is less than or equal to10%, 15%, 20%, 25%, or 30%. In this example, the stream sent to sugarseparation step 212 may have a total solids fraction of 25% to 40%, suchsolids including sugar, starch, fiber, protein, and/or germ, forexample. In this example, the stream sent to sugar separation step 212may have a total solids fraction of 27%.

The sugar stream from the sugar separation step 212 can be sent on to afurther processing step, such as a fermentation step where the sugarsare converted, e.g., via a fermenter, to alcohol, such as ethanol orbutanol or any other fermentation conversion process or similar sugarutilization/conversion process, followed by distillation and/orseparation of the desired component(s) (not shown), which can recoverthe alcohol or byproduct(s)/compound(s) produced, as is known in theart. The sugar stream can allow for recovery of a fermentation agentfrom the fermentation step. The fermentation agent can be recovered bymeans known in the art and can be dried as a separate product or, forexample, can be sent to a protein separation step or otherstreams/steps, in the system and method 200, which can allow for captureof the fermentation agent and/or used for further processing.Fermentation agent (such as yeast or bacteria) recycling can occur byuse of a clean sugar source. Following distillation or desiredseparation step(s), the system and method 200 can include any back endtype process(es), which may be known or unknown in the art to process,for example, the whole stillage. The fermentation step may be part of analcohol production system that receives a sugar stream that is not asdesirable or clean, i.e., “dirtier,” than the sugar stream being sentand subjected to the same fermentation step as the dirty sugar stream.Other options for the sugar stream, aside from fermentation, can includefurther processing or refining of the glucose to fructose or othersimple or even complex carbohydrates, processing into feed, microbebased fermentation (as opposed to yeast based) and other variouschemical, pharmaceutical, enzyme, amino acid, or nutraceuticalprocessing (such as propanol, isobutanol, citric acid or succinic acid),and the like, and the like. Such processing can occur via a reactor,including, for example, a catalytic or chemical reactor. In one example,the reactor is a fermenter.

Still referring to FIG. 4, the solid or heavy components (retentate)from the sugar separation step 212 can be sent to fermentation step 214.These heavier components or underflow, can be more concentrated in totalsolids, such as from 25% to 40%. In one example, these heaviercomponents or underflow, can be more concentrated in total solids, at28%. Optionally, the portion of the liquefied starch solution from theliquefaction step 207 and the solids portion from the solid/liquidseparation step 208 may be also subjected to the fermentation step 214.The fermentation step 214 is followed by distillation 216. At thedistillation tower, the fermented solution is separated from thestillage, which includes fiber, protein, and germ particles, to producealcohol. The fiber can be separated from the germ particles and protein(gluten) at a fiber/protein separation step 218 by differences inparticle sizes using a screen device, such as a filtration centrifuge,to remove the fiber therefrom. The screen openings normally will beabout 500 microns to capture amounts of tipcap, pericarp, as well asfine fiber, but can range from about 200 microns to about 1000 microns.

The centrate from the fiber/protein separation step 218 can go to anevaporator 220 to separate any oil therefrom and to produce syrup, whichcan be mixed with the DDG and dried, as represented by numeral 222, togive DDGS, such as for cows or pigs, particularly dairy cows.

In addition, an optional centrifugation step (not shown) may be providedto recover the xanthophyll content in the emulsion layer of therecovered oils and mixed with the protein by-product prior to drying toincrease the feed value. The overflow from the centrifuge(s) can go backto oil storage tanks (not shown).

With further reference now to FIG. 5, in this dry grind system andmethod 300, grains such as corn and/or corn particles, for example, canbe subjected to an optional first grinding step 302, which involves useof a disc mill, hammer mill, roller mill, pin mill, impact mill, flakingmill, grind mill, or the like, either in series or in parallel, to grindthe corn and/or corn particles to particle sizes less than about 5/64inch or, in another example, less than about 10/64 inch and allow forthe release of oil therefrom defining free oil. In one example, thescreen size for separating the particles can range from about 24/64 inchto about 2/64 inch. In another example, the resulting particle sizes arefrom about 50 microns to about 3 mm. The grinding also helps break upthe bonds between the fiber, protein, starch, and germ. In one example,screen size or resulting particle size may have little to no impact onthe ability to separate the sugar from the remaining kernel or similarraw material component(s). If the carbohydrate source is pre-ground orinitially in particulate form, the optional grind step 302 may beexcluded from the system and method 300.

Next, the ground corn flour can be mixed with backset liquid at slurrytank 304 to create a slurry. Optionally, fresh water may be added so asto limit the amount of backset needed here. An enzyme(s), such as alphaamylase, optionally can be added to the slurry tank 304 or in a slurryblender (not shown) between the optional first grinding step 302 and theslurry tank 304. The slurry may be heated at the slurry tank 304 fromabout 66° C. (150° F.) to about 93° C. (200° F.) for about 10 min toabout 120 min. The stream from the slurry tank 304 contains about 0.5lb/bu free oil, about 1.5 lb/bu germ (particle size ranges from about 50microns to about 3 mm), about 1.8 lb/bu grit (particle size ranges fromabout 50 microns to about 3 mm), which can include starch, and about4.25 lb/bu fiber (particle size ranges from about 50 microns to about 3mm).

The stream from the slurry tank 304 next may be subjected to an optionalsecond grinding/particle size reduction step 306, which may involve useof a disc mill, hammer mill, pin mill, impact mill, roller mill, flakingmill, grind mill, or the like, to further grind the corn particles toparticle sizes less than about 850 microns and allow for additionalrelease of oil and protein/starch complexes therefrom. In anotherexample, the particle sizes are from about 300 microns to about 650 mm.The grinding further helps continue to break up the bonds between thefiber, protein, and starch and facilitates the release of free oil fromgerm particles.

Prior to subjecting the stream from the slurry tank 304 to the optionalsecond grinding/particle size reduction step 306, the slurry may besubjected to an optional liquid/solid separation step 308 to remove adesired amount of liquids therefrom. The liquid/solid separation step308 separates a generally liquefied solution (about 60% to about 80% byvolume), which includes free oil, protein, and fine solids (which do notneed grinding), from heavy solids cake (about 20% to about 40% byvolume), which includes the heavier fiber, grit, and germ, which caninclude bound oil, protein, and/or starch. The liquid/solid separationstep 308 uses dewatering equipment, e.g., a paddle screen, a vibrationscreen, screen decanter centrifuge or conic screen centrifuge, apressure screen, a preconcentrator, a filter press, or the like, toaccomplish separation of the solids from the liquid portion. The finesolids can be no greater than 200 microns. In another example, the finesolids are no greater than 500 microns, which is generally dependentupon the screen size openings used in the liquid/solid separationdevice(s).

In one example, the dewatering equipment is a paddle screen, whichincludes a stationary cylinder screen with a high speed paddle withrake. The number of paddles on the paddle screen can be in the range of1 paddle per 4 to 8 inches of screen diameter. In another example, thedewatering equipment is a preconcentrator, which includes a stationarycylinder screen with a low speed screw conveyor. The conveyor pitch onthe preconcentrator can be about ⅙ to about ½ of the screen diameter.The number of paddles on the paddle screen and the conveyor pitch on thepreconcentrator can be modified depending on the amount of solids in thefeed. The gap between the paddle screen and paddle can range from about0.04 inch to about 0.2 inch. A smaller gap gives a drier cake withhigher capacity and purer fiber but loses more fiber to filtrate. Alarger gap gives a wetter cake with lower capacity and purer liquid(less insoluble solid). The paddle speed can range from 400 to 1200 RPM.In another example, the paddle speed can range from 800 to 900 RPM. Ahigher speed provides higher capacity but consumes more power. Onesuitable type of paddle screen is the FQ-PS32 paddle screen, which isavailable from Fluid-Quip, Inc. of Springfield, Ohio.

The screen for the dewatering equipment can include a wedge wire typewith slot opening, or a round hole, thin plate screen. The round holescreen can help prevent long fine fiber from going through the screenbetter than the wedge wire slot opening, but the round hole capacity islower, so more equipment may be required if using round hole screens.The size of the screen openings can range from about 45 microns to about500 microns. In another example, the screen openings can range from 100to 300 microns. In yet another example, the screen openings can rangefrom 200 to 250 microns. Smaller screen openings tend to increase theprotein/oil/alcohol yield with higher equipment and operation cost,whereas larger screen openings tend to lower protein/oil/alcohol yieldwith less equipment and operation cost.

The wet cake or dewatered solids portion of the stream at theliquid/solid separation step 308 (about 60% to about 65% water) next maybe subjected to the optional second grinding/particle size reductionstep 306, as described above. After milling, the solids can be mixedwith the liquefied starch solution from the liquid/solid separation step308, as shown, to form a heavy slurry then subjected to liquefactionstep 310.

In particular, the liquefaction step 310 itself can include multiplesteps as discussed above and shown in FIG. 3. In one embodiment, the pHcan be adjusted here to about 5.2 to about 5.8 and the temperaturemaintained between about 50° C. to about 100° C. so as to convert theinsoluble starch in the slurry to soluble or liquid starch. Other pHranges, such as from pH 3.5-7.0, may be utilized and an acid treatmentsystem using sulfuric acid, for example, may be used as well for pHcontrol and for conversion of the starches to sugars. The slurry may befurther subjected to jet cooking whereat the slurry is fed to a jetcooker, heated to about 120° C., held for about 2 min to about 30 min,then forwarded to a flash tank. The jet cooker creates a sheering forcethat ruptures the starch granules to aid the enzyme in reacting with thestarch inside the granule and for hydrating the starch molecules. Inanother embodiment, the slurry can be subjected to a secondary slurrytank whereat steam is injected directly to the secondary slurry tank andthe slurry is maintained at a temperature from about 80° C. to about100° C. for about 30 min to about one hour. In yet another embodiment,the slurry can be subjected to a secondary slurry tank with no steam. Inparticular, the slurry is sent to a secondary slurry tank without anysteam injection and maintained at a temperature of about 80° C. to about90° C. for 1 to 2 hours. Thereafter, the liquefied slurry may beforwarded to a holding tank for a total holding time of about 1 hour toabout 4 hours at temperatures of about 80° C. to about 90° C. tocomplete the liquefaction step 310. With respect to the liquefactionstep 310, pH, temperature, and/or holding time may be adjusted asdesired.

The slurry stream after the liquefaction step 310 has about 25% to about40% dry solids (DS) content with all the components contained in thecorn kernels, including starches/sugars, protein, fiber, germ, grit,oil, and salts, for example. Higher slurry streams with dry solids ofgreater than 50% may be incorporated with this system and method 300.There generally are three types of solids in the liquefaction stream:fiber, germ, and grit, which can include starch and protein, with allthree solids having about the same particle size distribution. Thestream from the liquefaction step 310 contains about 1.0 lb/bu free oil,about 1.5 lb/bu germ particle (size ranges from less about 50 microns toabout 1 mm), about 4.5 lb/bu protein (size ranges from about 50 micronsto about 1 mm), and about 4.25 lb/bu fiber (particle size ranges fromabout 50 microns to about 3 mm). A portion of the liquefied starchsolution from the liquefaction step 310 can optionally be subjected to afurther biochemical conversion processing step 318, as discussed furtherbelow.

After the liquefaction step 310 (but before any potentialsaccharification, fermentation, or other processing of the sugarstream), so as to provide a more desirable sugar stream, at least aportion of the liquefied starch solution can be subjected to asolid/liquid separation step 312. In particular, the solid/liquidseparation step 312 uses any suitable filtration device, e.g., apre-concentrator, paddle screen, pressure screen, fiber centrifuge, andthe like, to separate the liquid from the solid material. The screenopenings can range from about 50 microns to about 500 microns and willbe selected to desirably separate the fiber, grit, and germ particlesfrom the liquid, which primarily includes the liquefied starch solutionwith small amounts of oil, free protein (mainly gluten), and starch. Inone example, the screen openings are about 50 microns. The solidsportion from the solid/liquid separation step 312 can optionally besubjected to a further biochemical conversion processing step 318, asdiscussed further below.

The liquefied starch solution from the solid/liquid separation step 312can be sent to the saccharification step 314 whereat complexcarbohydrate and oligosaccharides are further broken down into simplesugars, particularly single glucose sugar molecules (i.e., dextrose) toproduce a liquefied mash. In particular, at the saccharification step314, the slurry stream may be subjected to a two-step cook process. Thefirst part of the cook process, in one example, includes adjusting thepH to about 3.5 to about 7.0, with the temperature being maintainedbetween about 30° C. to about 100° C. for 1 to 6 hours to furtherconvert the insoluble starch in the slurry to soluble starch,particularly dextrose. In another example, the pH can be 5.2 to 5.8 or5.5, for example. In another example, the temperature can be maintainedat 80° C. for about 5 hours. Also, an enzyme, such as alpha-amylase maybe added here. In one example, the amount of alpha-amylase may be fromabout 0.0035 wt % to about 0.004 wt % of the slurry stream. In anotherexample, the amount of alpha-amylase may be from about 0.02 wt % toabout 0.1 wt % of the total stream.

The second part of the cook process, in one example, may includeadjusting the pH to about 3.5 to about 5.0, with the temperature beingmaintained between about 30° C. to about 100° C. for about 10 minutes toabout 5 hours so as to further convert the insoluble starch in theslurry to soluble starch, particularly dextrose. In another example, thepH can be 4.5. In another example, the temperature can be maintainedfrom about 54° C. (130° F.) to about 74° C. (165° F.) for about 4 hoursor up to about 60 hours. An enzyme, such as glucoamylase, also may beadded here. In one example, the amount of glucoamylase may be from about0.01 wt % to about 0.2 wt % of the slurry stream. In another example,the amount of glucoamylase may be from about 0.08 wt % to about 0.14 wt% of the slurry stream. Other enzymes (e.g., cellulase, protease,phytase, etc.) or similar catalytic conversion agents may be added atthis step or previous steps that can enhance starch conversion to sugaror yield other benefits, such as fiber or cellulosic sugar release,conversion of proteins to soluble proteins, or the release of oil fromthe germ.

A saccharified sugar stream having a density of about 1.05 grams/cc toabout 1.15 grams/cc can result here. At this point, the saccharifiedsugar stream may be no less than about 90 DE. In another example, thesaccharified sugar stream may be no less than 20, 30, 40, 50, 60, 70, or80 DE. In this example, the saccharified sugar stream may not beconsidered desirable or “clean” enough, such as for use in biochemical(e.g., biofuel) production, because the total fermentable content of thestream may be no more than 75% of the total solids content in thestream. In this example, the saccharified sugar stream can have a totalsolids fraction of about 28% to about 40%, such solids including sugar,starch, fiber, protein, germ, oil, and ash, for example. In yet anotherexample, the total fermentable content of the stream is no more than 30,40, 50, 60, or 70% of the total solids content in the stream. Theremaining solids are fiber, protein, oil, and ash, for example.

After the saccharification step 314 (but before any potentialfermentation or processing of the sugar stream), so as to provide a moredesirable sugar stream, the saccharified sugar stream is subjected to asugar separation step 316, which can include a rotary vacuum filter,micro-filter, membrane filtration, precoat/diatomaceous earth filter,decanter, centrifuge, disc centrifuge, cyclone, dorclone, or the like,to produce a more desirable sugar stream, which may be considered apurified or refined sugar stream, by substantial separation of thesolids portion, primarily fiber, germ, and grit, which can includeprotein, from the liquid sugar portion, which primarily includes sugar(e.g., dextrose), residual oil, and fine solids. In one example, thefilter screen size here may be from about 0.1 microns to about 100microns. In another example, the filter screen size may be from about 5microns to about 50 microns. Due to the input of water, the sugar streamcan have a total solids fraction of 20% to 35%. In this example, thesugar stream here may be considered purified or refined enough becausethe total insoluble (unfermentable) solids fraction of the stream isless than 10%. In another example, the total insoluble (unfermentable)solids fraction of the stream is less than or equal to 7%. In anotherexample, the total insoluble (unfermentable) solids fraction of thestream is less than or equal to 5%. In another example, the totalinsoluble (unfermentable) solids fraction of the stream is less than orequal to 3%. In another example, the total insoluble (unfermentable)solids fraction of the stream is less than or equal to 1%. In stillanother example, the total insoluble (unfermentable) solids fraction ofthe stream is less than or equal to 10%, 15%, 20%, 25%, or 30%.

At this point, the separated sugar stream may be no less than about 90DE. In another example, the saccharified sugar stream may be no lessthan 20, 30, 40, 50, 60, 70, or 80 DE. In this example, the sugar streamhere may be considered desirable or “clean” enough, such as for use inbiochemical production, because the total insoluble (unfermentable)solids fraction of the stream is less than or equal to 10% of the totalsolids of the stream. In another example, the total insoluble(unfermentable) solids fraction of the stream is less than or equal to7%. In another example, the total insoluble (unfermentable) solidsfraction of the stream is less than or equal to 5%. In another example,the total insoluble (unfermentable) solids fraction of the stream isless than or equal to 3%. In another example, the total insoluble(unfermentable) solids fraction of the stream is less than or equal to1%. In still another example, the total insoluble (unfermentable) solidsfraction of the stream is less than or equal to 10%, 15%, 20%, 25%, or30%. In this example, the stream sent to sugar separation step 316 mayhave a total solids fraction of about 27%, or in a range of about 20% toabout 35%, such solids including sugar, starch, fiber, protein, and/orgerm, for example.

The sugar separation step 316 may be replaced by, or additionallyinclude, ultrafiltration, carbon column filtration, filter press,flotation, adsorption, and/or demineralization technologies (e.g., ionexchange). Resin refining, which includes a combination of carbonfiltration and demineralization in one step, can also be utilized forrefining the sugars. Additionally, due to a low solids content of thesugar stream here, an optional evaporation step (not shown) may be addedhereafter to further concentrate the total solids fraction.

As described above, the heavy or solids (raffinate) components from thesugar separation step 316 can be sent to meet up with the separatedsolids portion from the solid/liquid separation step 312 and theoptional portion of the liquefied starch solution from the liquefactionstep 310 and subjected to biochemical conversion process step 318. Theseheavier components, or underflow, can be more concentrated in totalsolids at about 28%.

In one example, prior to the biochemical conversion process step 318,the combined streams may be subjected to an optional thirdgrinding/particle size reduction step 322, which may involve use of adisc mill, hammer mill, pin mill, impact mill, roller mill, flakingmill, grind mill, or the like for further grinding of particles. Priorto subjecting the combined streams to the optional thirdgrinding/particle size reduction step 322, the stream may be subjectedto an optional liquid/solid separation step 324 to remove a desiredamount of liquids therefrom. The liquid/solid separation step 324separates the liquid portion of the combined stream, which can includefree oil, protein, and fine solids (which do not need grinding), fromremaining heavy solids cake, which includes the heavier fiber, grit, andgerm, which can include bound oil, protein, and/or starch. Theliquid/solid separation step 324 uses dewatering equipment, e.g., apaddle screen, a vibration screen, screen decanter centrifuge or conicscreen centrifuge, a pressure screen, a preconcentrator, a filter press,or the like, to accomplish separation of the solids from the liquidportion. The fine solids can be no greater than 200 microns. In anotherexample, the fine solids are no greater than 500 microns, which isgenerally dependent upon the screen size openings used in theliquid/solid separation device(s).

In one example, the dewatering equipment is a paddle screen, whichincludes a stationary cylinder screen with a high speed paddle withrake. The number of paddles on the paddle screen can be in the range of1 paddle per 4 to 8 inches of screen diameter. In another example, thedewatering equipment is a preconcentrator, which includes a stationarycylinder screen with a low speed screw conveyor. The conveyor pitch onthe preconcentrator can be about ⅙ to about ½ of the screen diameter.The number of paddles on the paddle screen and the conveyor pitch on thepreconcentrator can be modified depending on the amount of solids in thefeed. The gap between the paddle screen and paddle can range from about0.04 to about 0.2 inch. A smaller gap gives a drier cake with highercapacity and purer fiber but loses more fiber to filtrate. A larger gapgives a wetter cake with lower capacity and purer liquid (less insolublesolid). The paddle speed can range from 400 to 1200 RPM. In anotherexample, the paddle speed can range from 800 to 900 RPM. A higher speedprovides higher capacity but consumes more power. One suitable type ofpaddle screen is the FQ-PS32 paddle screen, which is available fromFluid-Quip, Inc. of Springfield, Ohio.

The screen for the dewatering equipment can include a wedge wire typewith slot opening, or a round hole, thin plate screen. The round holescreen can help prevent long fine fiber from going through the screenbetter than the wedge wire slot opening, but the round hole capacity islower, so more equipment may be required if using round hole screens.The size of the screen openings can range from about 45 microns to about500 microns. In another example, the screen openings can range from 100to 300 microns. In yet another example, the screen openings can rangefrom 200 to 250 microns.

The wet cake or dewatered solids portion of the stream at theliquid/solid separation step 324 next may be subjected to the optionalthird grinding/particle size reduction step 322, as described above.After milling, the solids can be mixed with the liquid from theliquid/solid separation step 324, as shown, to form a solid/liquidstream then subjected to the biochemical conversion process step 318.

In an embodiment, the biochemical conversion step 318 is a fermentationstep where the sugars are converted, e.g., via a fermenter, to alcohol,such as ethanol or butanol or any other fermentation conversion processor similar sugar utilization/conversion process, followed bydistillation and/or separation of the desired component(s) (not shown),which can recover the alcohol or byproduct(s)/compound(s) produced, asis described above with respect to the system and method 200. Followingdistillation or desired separation step(s), the system and method 300can include any back end type process(es), which may be known or unknownin the art to process, for example, the whole stillage. The fermentationstep may be part of an alcohol production system that receives a sugarstream that is not as desirable or clean, i.e., “dirtier,” than thesugar stream being sent and subjected to the same fermentation step asthe dirty sugar stream. Other options for the solids stream, aside fromfermentation, can include further processing or refining of the solidsinto feed, microbe based fermentation (as opposed to yeast based) andother various chemical, pharmaceutical, enzyme, amino acid, ornutraceutical processing (such as propanol, isobutanol, citric acid orsuccinic acid), and the like, and the like. Such processing can occurvia a reactor, which can include a fermenter.

The sugar stream from the sugar separation step 316 can be sent on to afurther processing step, such as a fermentation step where the sugarsare converted, e.g., via a fermenter, to alcohol, such as ethanol orbutanol or any other fermentation conversion process or similar sugarutilization/conversion process, followed by distillation and/orseparation of the desired component(s) (not shown), which can recoverthe alcohol or byproduct(s)/compound(s) produced, as is known in theart. The sugar stream can allow for recovery of a fermentation agentfrom the fermentation step. The fermentation agent can be recovered bymeans known in the art and can be dried as a separate product or, forexample, can be sent to a protein separation step or otherstreams/steps, in the system and method 300, which can allow for captureof the fermentation agent and/or used for further processing.Fermentation agent (such as yeast or bacteria) recycling can occur byuse of a clean sugar source. Following distillation or desiredseparation step(s), the system and method 300 can include any back endtype process(es), which may be known or unknown in the art to process,for example, the whole stillage. The fermentation step may be part of analcohol production system that receives a sugar stream that is not asdesirable or clean, i.e., “dirtier,” than the sugar stream being sentand subjected to the same fermentation step as the dirty sugar stream.Other options for the sugar stream, aside from fermentation, can includefurther processing or refining of the glucose to fructose or othersimple or even complex carbohydrates, processing into feed, microbebased fermentation (as opposed to yeast based) and other variouschemical, pharmaceutical, enzyme, amino acid, or nutraceuticalprocessing (such as propanol, isobutanol, citric acid or succinic acid),and the like. Such processing can occur via a reactor, including, forexample, a catalytic or chemical reactor. In one example, the reactor isa fermenter.

With further reference now to FIG. 6, the system and method 200 a issimilar in most all respects to the system and method 200 of FIG. 4,with the exception of the location of saccharification step 210 relativeto the solid/liquid separation step 208, as discussed below.

After the liquefaction step 207, the liquefied sugar stream can besubjected directly to the saccharification step 210 whereat complexcarbohydrate and oligosaccharides are further broken down into simplesugars, particularly single glucose sugar molecules (i.e., dextrose) toproduce a liquefied mash. In particular, at the saccharification step210, the slurry stream may be subjected to a two-step cook process, asdescribed above for the saccharification step 210. A saccharified sugarstream having a density of about 1.05 grams/cc to about 1.15 grams/cccan result here. At this point, the saccharified sugar stream may be noless than about 90 DE. In another example, the saccharified sugar streammay be no less than 20, 30, 40, 50, 60, 70, or 80 DE. In this example,the saccharified sugar stream may not be considered desirable or “clean”enough, such as for use in biochemical (e.g., biofuel) production,because the total fermentable content of the stream may be no more than75% of the total solids content in the stream. In this example, thesaccharified sugar stream can have a total solids fraction of about 25%to about 40%, such solids including sugar, starch, fiber, protein, germ,oil, and ash, for example. In yet another example, the total fermentablecontent of the stream is no more than 20%, 30%, 40%, 50%, 60%, 70%, or80% of the total solids content in the stream. The remaining solids arefiber, protein, oil, and ash, for example.

After the saccharification step 210 (but before any fermentation orother processing of the sugar stream), so as to provide a more desirablesugar stream, the saccharified sugar stream can be subjected tosolid/liquid separation step 208. In particular, the solid/liquidseparation step 208 uses any suitable filtration device, e.g., apre-concentrator, paddle screen, pressure screen, fiber centrifuge,decanter, and the like, to separate the liquid from the solid material,as described above for the solid/liquid separation step 208.

After the solid/liquid separation step 208 (but before any potentialfermentation or processing of the sugar stream), so as to provide a moredesirable sugar stream, the saccharified sugar stream can be subjectedto the sugar separation step 212. The solids portion from thesolid/liquid separation step 208 can be sent, along with the optionalportion of the liquefied starch solution from the liquefaction step 207,to the fermentation step 214.

With further reference now to FIG. 7, the system and method 300 a issimilar in most all respects to the system and method 300 of FIG. 5,with the exception of the location of the saccharification step 314relative the solid/liquid separation step 312, as discussed below.

After the liquefaction step 310, the liquefied starch solution can besent directly to the saccharification step 314 whereat complexcarbohydrate and oligosaccharides are further broken down into simplesugars, particularly single glucose sugar molecules (i.e., dextrose) toproduce a liquefied mash. In particular, at the saccharification step314, the slurry stream may be subjected to a two-step cook process, asdescribed above for the saccharification step 314. A saccharified sugarstream having a density of about 1.05 grams/cc to about 1.15 grams/cccan result here. At this point, the saccharified sugar stream may be noless than about 90 DE. In another example, the saccharified sugar streammay be no less than 20, 30, 40, 50, 60, 70, or 80 DE. In this example,the saccharified sugar stream may not be considered desirable or “clean”enough, such as for use in biochemical (e.g., biofuel) production,because the total fermentable content of the stream may be no more than75% of the total solids content in the stream. In this example, thesaccharified sugar stream can have a total solids fraction of about 25%to about 40%, such solids including sugar, starch, fiber, protein, germ,oil, and ash, for example. In yet another example, the total fermentablecontent of the stream is no more than 20%, 30%, 40%, 50%, 60%, 70%, or80% of the total solids content in the stream. The remaining solids arefiber, protein, oil, and ash, for example.

After the saccharification step 314, so as to provide a more desirablesugar stream, the saccharified sugar stream can be subjected tosolid/liquid separation step 312. In particular, the solid/liquidseparation step 312 uses any suitable filtration device, e.g., apre-concentrator, paddle screen, pressure screen, fiber centrifuge,decanter, and the like, to separate the liquid from the solid material.The screen openings can range from about 50 microns to about 500 micronsand will be selected to desirably separate the fiber, grit, and germparticles from the liquid, which primarily includes the liquefied starchsolution with small amounts of oil, free protein (mainly gluten), andstarch. In one example, the screen openings are about 50 microns. Theseparated solids portion from the solid/liquid separation step 312 canoptionally be subjected to the further biochemical conversion processingstep 318.

After the solid/liquid separation step 312 (but before any potentialfermentation or processing of the sugar stream), so as to provide a moredesirable sugar stream, the saccharified sugar stream is subjected tothe sugar separation step 316. The heavy or solids components from thesugar separation step 316 can be sent to meet up with the separatedsolids portion from the solid/liquid separation step 312 and theoptional portion of the liquefied starch solution from the liquefactionstep 310 and subjected to biochemical conversion process step 318.

With further reference now to FIG. 8, the system and method 200 b issimilar in most all respects to the system and method 200 of FIG. 4,with the exception of the removal of solid/liquid separation step 208,as discussed below.

After the liquefaction step 207, at least a portion of the liquefiedsugar stream can be subjected directly to the saccharification step 210whereat complex carbohydrate and oligosaccharides are further brokendown into simple sugars, particularly single glucose sugar molecules(i.e., dextrose) to produce a liquefied mash. In particular, at thesaccharification step 210, the slurry stream may be subjected to atwo-step cook process, as described above for the saccharification step210. A saccharified sugar stream having a density of about 1.05 grams/ccto about 1.15 grams/cc can result here. At this point, the saccharifiedsugar stream may be no less than about 90 DE. In another example, thesaccharified sugar stream may be no less than 20, 30, 40, 50, 60, 70, or80 DE. In this example, the saccharified sugar stream may not beconsidered desirable or “clean” enough, such as for use in biochemical(e.g., biofuel) production, because the total fermentable content of thestream may be no more than 75% of the total solids content in thestream. In this example, the saccharified sugar stream can have a totalsolids fraction of about 25% to about 40%, such solids including sugar,starch, fiber, protein, germ, oil, and ash, for example. In yet anotherexample, the total fermentable content of the stream is no more than20%, 30%, 40%, 50%, 60%, 70%, or 80% of the total solids content in thestream. The remaining solids are fiber, protein, oil, and ash, forexample.

After the saccharification step 210 (but before any potentialfermentation or other processing of the sugar stream), so as to providea more desirable sugar stream, the saccharified sugar stream can bedirectly subjected to the sugar separation step 212.

Further modifications can be made to the above systems and methods 200,200 a, 200 b, 300, 300 a to improve co-product recovery, such as oilrecovery using surfactants and other emulsion-disrupting agents. In oneexample, emulsion-disrupting agents, such as surfactants or flocculants,may be added prior to steps in which emulsions are expected to form orafter an emulsion forms in the method. For example, emulsions can formduring centrifugation such that incorporation of surfactants prior to orduring centrifugation can improve oil separation and recovery. In oneexample, the syrup stream pre-oil separation can also have emulsionbreakers, surfactants, and/or flocculants added to the evaporationsystem to aid in enhancing the oil yield. This may result in anadditional 0.05 to 0.5 lb/bu oil yield gain.

While the present invention has been illustrated by a description ofvarious embodiments and while these embodiments have been described inconsiderable detail, it is not the intention of the applicant torestrict or in any way limit the scope of the appended claims to suchdetail. For example, various enzymes (and types thereof) such asamylase, alpha-amylase, glucoamylase, fungal, cellulase, cellobiose,protease, phytase, and the like can be optionally added, for example,before, during, and/or after any number of steps in the systems andmethods 200, 200 a, 200 b, 300, 300 a including the slurry tank 204,304, the second grinding step 205, 306, the liquefaction step 207, 310,and/or the saccharification step 210, 314 such as to enhance theseparation of components, such as to help break the bonds betweenprotein, starch, and fiber and/or to help convert starches to sugarsand/or help to release free oil. In addition, temperature, pH,surfactant, and/or flocculant adjustments may be adjusted, as needed ordesired, at the various steps throughout the systems and methods 200,200 a, 200 b, 300, 300 a including at the slurry tank 204, 304, etc.,such as to optimize the use of enzymes or chemistries. Additionaladvantages and modifications will readily appear to those skilled in theart. Thus, the invention in its broader aspects is therefore not limitedto the specific details, representative apparatus and method andillustrative example shown and described. Accordingly, departures may bemade from such details without departing from the spirit or scope ofapplicant's general inventive concept.

What is claimed is:
 1. A method for producing a sugar stream from agrain feedstock, comprising: mixing ground grain particles derived froman initial feedstock of grain and/or grain components with a liquid toproduce a slurry that comprises starch; subjecting the slurry toliquefaction to provide a liquified starch solution, which includessolids; prior to saccharification, separating a first portion of theliquefied starch solution, via a paddle screen, into a solids portionand a liquid portion, wherein the liquid portion includes starch, andsubjecting a second portion of the liquefied starch solution, whichcomprises the remaining portion of the solids, directly to an ethanolfermentation process; thereafter, subjecting the liquid portion tosaccharification to convert the starch to simple sugars and produce asaccharified stream that comprises the simple sugars; aftersaccharification but prior to further processing of the simple sugars,directly separating the entire saccharified stream, via microfiltration,into a first solids portion and a first liquid portion that comprisesthe simple sugars, wherein the first liquid portion comprises a sugarstream having a dextrose equivalent of at least 20 DE and a totalunfermentable solids fraction that is less than or equal to 30% of atotal solids content and; thereafter, rejoining the solids portion,obtained by subjecting the first portion of the liquefied starchsolution to the separation via the paddle screen, with the first solidsportion, obtained by subjecting the saccharified stream to themicrofiltration, to provide a rejoined solids portion, and separatelysubjecting the rejoined solids portion, which comprises residual sugars,directly to the ethanol fermentation process along with the secondportion of the liquefied starch solution, which includes the remainingportion of the solids, whereby the residual sugars are fermented.
 2. Themethod of claim 1 further comprising, after mixing the grain particleswith the liquid to produce the slurry and prior to subjecting the slurryto liquefaction, separating the slurry into a slurry solids portion anda slurry liquid portion that comprises the starch, grinding the slurrysolids portion to produce a ground slurry solids portion, and rejoiningthe slurry liquid portion with the ground slurry solids portion toreconstitute the slurry prior to subjecting the slurry to liquefaction.3. The method of claim 1 further comprising subjecting at least aportion of the sugar stream to at least one of carbon filtration, ionexchange, or evaporation.
 4. The method of claim 1 further comprisingsubjecting at least a portion of the sugar stream to at least one ofcarbon filtration, ion exchange, or evaporation followed by a sugarconversion process to produce a biochemical.
 5. The method of claim 4wherein the sugar conversion process is fermentation.
 6. The method ofclaim 4 wherein the sugar conversion process includes a catalytic orchemical reaction.
 7. The method of claim 1 further comprisingsubjecting at least a portion of the sugar stream to carbon filtration,followed by ion exchange, and followed by evaporation.
 8. The method ofclaim 1 further comprising subjecting at least a portion of the sugarstream to a sugar conversion process to produce a biochemical.
 9. Amethod for producing a sugar stream from a grain feedstock, comprising:mixing ground grain particles derived from an initial feedstock of grainand/or grain components with a liquid to produce a slurry that comprisesstarch; subjecting the slurry to liquefaction to provide a liquefiedstarch solution; prior to saccharification, mechanically separating afirst portion of the liquefied starch solution into a solids portion anda liquid portion, wherein the liquid portion includes starch, andsubjecting a second portion of the liquefied starch solution, whichcomprises the remaining portion of the solids, directly to an ethanolfermentation process; thereafter, subjecting the liquid portion tosaccharification to convert the starch to simple sugars and produce asaccharified stream that comprises the simple sugars; aftersaccharification but prior to further processing of the simple sugars,directly separating the entire saccharified stream into a first solidsportion and a first liquid portion that comprises the simple sugars,wherein the first liquid portion comprises a sugar stream having adextrose equivalent of at least 20 DE and a total unfermentable solidsfraction that is less than or equal to 30% of a total solids content;and thereafter, rejoining the solids portion, obtained by mechanicallyseparating the first portion of the liquefied starch solution, with theseparated first solids portion to provide a rejoined solids portion, andseparately subjecting the rejoined solids portion, which comprisesresidual sugars, directly to the ethanol fermentation process along withthe second portion of the liquefied starch solution, which includes theremaining portion of the solids, whereby the residual sugars arefermented.
 10. The method of claim 9 further comprising subjecting atleast a portion of the sugar stream to a sugar conversion process toproduce a biochemical.
 11. The method of claim 9 further comprisingsubjecting at least a portion of the sugar stream to at least one ofcarbon filtration, ion exchange, or evaporation followed by a sugarconversion process to produce a biochemical.
 12. The method of claim 11wherein subjecting at least a portion of the sugar stream to at leastone of carbon filtration, ion exchange, or evaporation comprisessubjecting at least a portion of the sugar stream to carbon filtration,followed by ion exchange, followed by evaporation, and then followed bythe sugar conversion process to produce a biochemical.
 13. The method ofclaim 9 wherein after saccharification but prior to further processingof the simple sugars, the saccharified stream is separated, viafiltration, into a first solids portion and a first liquid portion thatcomprises the simple sugars.
 14. The method of claim 13 wherein thefiltration is microfiltration.
 15. The method of claim 9 whereinmechanically separating the first portion of the liquefied starchsolution comprises mechanically separating the first portion of theliquefied starch solution, via a paddle screen, into a solids portionand a liquid portion, wherein the liquid portion includes starch. 16.The method of claim 9 further comprising, after mixing the grainparticles with the liquid to produce the slurry and prior to subjectingthe slurry to liquefaction, separating the slurry into a slurry solidsportion and a slurry liquid portion that comprises the starch, grindingthe slurry solids portion to produce a ground slurry solids portion, andrejoining the slurry liquid portion with the ground slurry solidsportion prior to subjecting the slurry to liquefaction.
 17. The methodof claim 10 wherein the sugar conversion process is fermentation. 18.The method of claim 10 wherein the sugar conversion process includes acatalytic or chemical reaction.
 19. The method of claim 9 furthercomprising subjecting at least a portion of the sugar stream to at leastone of carbon filtration, ion exchange, or evaporation.